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ID:38584040
大小:78.62 KB
页数:6页
时间:2019-06-15
《Science Revision Biology 新加坡初二生物》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Sec2ScienceRevisionBiologyChapterD4MovementofSubstancesIntoandOutofcellsThemovementofsubstancesinandoutofthecellsoccursinthreeways:Diffusion,Osmosis(passiveprocess)andActiveTransport(requiredenergy).Diffusionisthemovementofparticlesfromaregionofhigherconcentrationtoaregio
2、noflowerconcentrationdownaconcentrationgradient.Diffusionbetweentwosolutionstopswhenthesolutionshomogeneous.Partiallypermeablemembranes---donotallowallmoleculestopassthroughOsmosisisthemovementofwatermoleculesfromaregionofhigherwaterpotentialtoaregionoflowerwaterpotential
3、throughapartiallypermeablePlantsabsorbnutrientsthroughthediffusionprocessandwaterthroughtheosmosisprocessWatermoleculesmovefromadilutedsolutiontoaconcentratedsolutionduringosmosisCarbondioxidediffuseintoaleafcellwhileoxygendiffuseoutofitduringthephotosynthesisprocessOsmos
4、isDiffusionItinvolvesthemovementofwatermoleculesonlyItinvolvesthemomentofanymoleculesTakeplacethroughasemi-permeablemembraneTakeplacewithorwithoutasemi-permeablemembraneOsmosis:~Plantcell-inwater[waterentercell](thecellbecometurgid)-inconcentratedsugarsolution[waterleaves
5、cell](thecellbecomessoft)~Animalcell-inwater[waterenterscellcontinuously](thecellswellsandeventuallybursts)-inconcentrated[waterleavescell](thecellshrinkstoasmallsize)Diffusioninlivingorganisms--unicellularorganisms--photosynthesis--thehumanbodyOsmosisinlivingorganisms--r
6、oots--stemsandleaves--sprayingfruitsActiveTransport--substancesmovefromaregionoflowerconcentrationtoaregionofhigherconcentrationD5TransportinLivingThingsPlantsabsorbwaterthroughosmosis.Transpirationonlytakesplaceinplants.Hearts--anorganwhichpumpsbloodroundthebody--pumpblo
7、odtoallpartsofthebodyBlood--aliquidwhichcarriesmaterials--redbloodcells,platelets,bloodplasma,whitebloodcellsComponentFunctionRedBloodCells红血球~carryoxygenfromthelungtovariouspartsofthebody~containhaemoglobintohelpthemtransportoxygenmoreefficiently~carriesasmallamountofcar
8、bondioxideforremovalPlatelets血小板~preventbloodlossfromdamagedbloodvesselsbyformingclotsBloodPlasm
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